A rubber glove is used in a wide range of applications such as housework, a food-related industry, a precision industry, or medical care. Conventionally, as a rubber glove having a high tensile strength and an excellent oil resistance, a dip-formed article obtained by dip-forming a carboxy-modified acrylonitrile-butadiene copolymer latex has been frequently used.
For example, Patent Literatures 1 to 7 disclose a carboxy-modified acrylonitrile-butadiene copolymer latex. A rubber glove obtained by dip-forming the latex described in these literatures has a better oil resistance than a rubber glove obtained from a natural rubber latex, and therefore has been widely used. In addition, recently, demand for a carboxy-modified acrylonitrile-butadiene copolymer latex as a synthetic rubber has been further increased because of a problem of a protein allergy caused by a protein contained in a natural rubber.
Meanwhile, a rubber glove is required to have various characteristics, examples of which include a characteristic that the glove stretches according to movement of the finger and has a good texture in order to prevent fatigue of the hand even after being worn for a long time (the glove has a small 300% tensile stress and a large elongation), a characteristic that the glove is not torn during working (the glove has a sufficient tensile strength), and a characteristic that the glove is not deteriorated even when a work touching oil and fat is performed (the glove has an oil resistance).
However, a glove based on such a carboxy-modified acrylonitrile-butadiene copolymer as described in Patent Literatures 1 to 7 has an excellent oil resistance, but has the following problems. That is, such a copolymer has a characteristic that a balance among physical properties such as a mechanical strength (a tensile strength, a tear strength, and the like), an elongation, or a flexibility varies largely according to a monomer composition to be polymerized. Therefore, for example, when the content of an acid or the content of a nitrile in a copolymer is increased relatively in order to improve a tensile strength, significantly lowering of a flexibility, an elongation, and a tear strength is occurred disadvantageously. Accordingly, such a dip-formed article has been required to further improve a tensile strength and a tear strength while a desired flexibility and an elongation (texture) are secured.